1. Field of Invention
This invention relates generally to radio frequency (RF) and microwave communications and more specifically, to an improved antenna design for RF and microwave communication devices.
2. Description of Related Art
Generally, an antenna can be modeled as a half wave dipole antenna. The length of a half wave dipole antenna is equal to a half-wavelength at the frequency of operation. A dipole antenna, spiral antenna, bow tie antenna, and log-periodic antenna have two arms. Other types of antennas, such as a monopole antenna, planar inverted-F antenna (PIFA) antenna, helix antenna, and patch antenna have a single arm, but the ground plane acts as a second arm for it to radiate.
Cellular phone and communication device manufacturers are struggling to meet over-the air (OTA) performance requirements due to antenna limitations. To provide the best antenna, antenna length has to be large, but large antennas cannot be accommodated into small devices. Conventional techniques fold or bend the antenna to save space, but the trade-off is decreased antenna efficiency, bandwidth, and gain.
Today's communication devices have to meet customer preferences by being sophisticated, easy to operate, and portable, i.e., small in size. Designing a small communication device is a huge challenge for low frequency operations. Radio frequency (RF) (e.g., 30 Hz-3 GHz) and microwave frequency (3 GHz-300 GHz) operation makes it impossible to have adequate antenna efficiency, gain, and bandwidth if not enough antenna arm length is provided for a dipole antenna or not enough ground plane length is provided for monopole, PIFA, or circular antenna. For the purposes of simplifying the present disclosure, reference to radio waves or RF includes microwaves or microwave frequencies.
Therefore, there exists a need to optimize antenna design in small form factor communications devices operating at low frequencies.